The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Natural gas is a common fuel source that has many important applications. Natural gas is often transported in its liquid form, referred to herein as liquid natural gas (LNG), since it takes up much less volume. Upon arriving at its destination near a source of use (e.g., power plant) the LNG can be converted back into a gaseous state via a regasification process.
Numerous regasification devices, systems, and processes are known. For example, Conversion Gas Imports, L.P. (“CGI”) is the owner of the following U.S. Patents related to regasification: U.S. Pat. Nos. 5,511,905; 6,739,140; 6,813,893; 6,880,348; 6,848,502, 6,945,055, 7,036,325. These and all other referenced extrinsic materials are incorporated herein by reference in their entirety. Where a definition or use of a term in a reference that is incorporated by reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein is deemed to be controlling.
Some of the patents listed above describe designs for a LNG receiving terminal using salt cavern storage. The LNG may come directly from a ship or from a conventional storage tank. The LNG receiving terminal may be located onshore or offshore.
Some of these patents also describe methods for warming LNG and storage in compensated or uncompensated salt caverns, which is referred to as the Bishop Process™.
Some of the patents listed above also describe pipe-in-pipe heat exchanger designs. One embodiment of the LNG receiving terminal uses multiple salt caverns for blending of gas from different sources to achieve a pipeline standard BTU (i.e., British Thermal Units) content.
Unfortunately, current regasification technology suffers from numerous drawbacks. For example, some of the patents listed above describe systems in which a warming fluid (e.g., seawater) is discharged into the sea after use. The discharged fluid can have a negative impact on the environment (e.g., the discharged seawater is often too cold and can kill fish eggs, thus reducing the population of sea life).
The company GTherm has recently conceived of a new approach for power generation that relies on geothermal wells (see FIG. 1). The GTherm approach utilizes a closed-loop system and a circulating fluid. The circulating fluid is heated as it passes through a geothermal well and cools as it passes through an evaporator. GTherm has also conceived of applying similar principles to enhanced oil recovery systems. However, to the best of applicant's knowledge, those of ordinary skill in the art have failed to provide a closed-loop system with a circulating fluid that utilizes heat from geothermal wells for LNG regasification systems.
US20070079617 describes methods and systems for geothermal vaporization of liquefied natural gas. However, the system described in US20070079617 does not appear to provide a pipe-in-pipe heat exchanger to efficiently utilize heat from geothermal wells.
Thus, there remains a need for improved systems and methods for LNG regasification.